Japanese Non-examined Patent Publication No.11-260960 discloses a sensor package for accommodating a semiconductor sensor chip such as a semiconductor acceleration sensor chip. This sensor package is a type of surface-mounted package and is adapted to be mounted on a surface of a printed board. This sensor package comprises a case for accommodating the semiconductor sensor chip and output electrodes provided on an undersurface of the case. The output electrodes are soldered to a printed board for connecting the semiconductor sensor chip electrically to an electric circuit of the printed board as well as for holding the sensor package physically on the printed board. The case has a bottom wall for fixing the semiconductor sensor chip on its upper surface. The output electrodes are formed in the undersurface of the bottom wall. A plurality of concave grooves are also formed on the undersurface of the bottom wall, which give a certain degree of deformation ability to the bottom wall. That is, these grooves enable the bottom wall outside the grooves to be bended, so that, even if the printed board is deformed by, for example, thermal expansion, the output electrode provided on the undersurface of the bottom wall can be prevented from separating from the printed board by the bottom wall following the deformation to some extent. Furthermore, it can be thought that the grooves buffer a distortion caused by the deformation of the printed board and make it difficult for the distortion to reach the semiconductor sensor chip so that a device carrying the sensor package can be prevented from introducing a malfunction due to an unnecessary distortion added to the semiconductor sensor chip.
In many cases, for mounting the semiconductor sensor chip on the bottom wall of the sensor package, die bonding paste is first applied to a predetermined area on the bottom wall, then the semiconductor sensor chip is laid on the predetermined area exactly, while being monitored by means of a CCD camera. On this occasion, if the die bonding paste has been applied superfluously, the die bonding paste may climb the semiconductor sensor chip when the sensor chip is laid on the bottom wall and have an adverse effect on movement of the semiconductor sensor chip. Furthermore, in order to monitor the location by means of the CCD camera, a certain mark must be formed, which results in increased costs for fabricating the sensor package.
As mentioned above, prior sensor packages can prevent the distortion caused by the deformation of the printed board from reaching the semiconductor sensor chip, but still have problems related to prevention of the climbing of the die bonding paste and improvement in the positioning of the semiconductor sensor chip.